<p>Piezocatalysis has shown great potential in non-invasive medical treatment and pollutant removal. Since piezocatalysis usually occurs in solution, capturing the effect of the solution is essential in mechanistic study. However, conventional theoretical methods cannot handle the interaction between the solution and the piezocatalysts, which leads to a huge discrepancy between the simulated scenarios and the actual working condition of piezocatalysis. Here, we first propose the quantum-continuum-electrochemical (QCE) method to elucidate the general mechanism of piezocatalysis in solution. Taking barium titanate (BaTiO₃, BTO) as an example, our QCE method can directly calculate the redox potential of the piezocatalyst and quantitatively predict of how material and solution properties modulate piezocatalytic activity. Our work provides a brand-new theoretical framework to dissect the piezocatalysis in solution, which not only advances the mechanistic understanding of piezocatalysis but also brings guidance to the experimental design of piezocatalysts for non-invasive medical treatment.</p>